0 to 9 are stored as \(48\) to \(57\). A to Z are stored as \(65\) to \(90\). a to z are stored as \(97\) to \(122\). char variable type in MATLAB. 'Hello World!' is a string, and char([72 101 108 108 111 32 87 111 114 108 100 33]) represents the same string. ['Hello ', 'World' '!'] is the same as 'Hello World!'. append(x, y, ...) also combines the strings \(x, y, ...\), for example, append('Hello ', 'World', '!') returns 'Hello World!'. strcat(x, y, ...) combines (or conCATenate) the strings \(x, y, ...\) and removes trailing spaces, for example, strcat('Hello ', 'World', '!') returns 'HelloWorld!'. 'abc' + 1 'abc1' 'bcd' text = 'a':'e'; text(end:-1:1) 'dcb' 'edcba' num2str(x, n) converts a number \(x\) (not ASCII code) to a string, rounded to \(n\) significant digits (different from \(n\) decimal places), for example, num2str(pi, 4) is the same as 3.142 or char([51 46 49 52 50]). str2num(x) converts a string back to a number or a matrix, for example, str2num('3.142') returns the number \(3.142\) and str2num('1 2; 3 4') returns the matrix \(\begin{bmatrix} 1 & 2 \\ 3 & 4 \end{bmatrix}\). str2num('1') + num2str(1) '11' '50' string variable type that stores multiple characters as a single object so that multiple strings can be stored in a vector without getting combined into one, for example, ['a' 'b' 'c'] is the same as 'abc' but ["a" "b" "c"] stays a vector and "a" + "b" + "c" is the same as "abc". string('abc') becomes "abc" and char("abc") becomes 'abc'. strfind(x, y) finds the indices of all occurrences of \(y\) in \(x\), for example, strfind('aabb', 'a') returns \(\begin{bmatrix} 1 & 2 \end{bmatrix}\). strrep(x, o, n) or replace(x, o, n) replaces all occurrences of \(o\) in \(x\) by \(n\) and returns the new string, for example, strrep('aabb', 'b', 'c') returns 'aacc' and replace('aabb', ["a", "b"], ["c", "d"]) return 'ccdd'. blanks(n) creates a string with \(n\) spaces. '' (two single quotation marks, note one double quotation mark) is '. %% is %. \\ is backslash \. \n is new line. \t is tab. disp(x) displays the string \(x\). It does not store \(x\) in the variable ans. fprintf(x, v1, v2, ...) displays a string with %s (string), %i (integer), %f (floating point), %e (scientific notation) replaces by \(v_{1}, v_{2}, ...\). % to set the field width (text length) for the string, for example, %5s and %-5i make sure that the displayed string has length \(\geq 5\) by adding spaces when necessary. A positive number means added spaces are on the left and a negative number means added spaces are on the right. . followed by a number for %f to set the precision, the number of digits after the decimal point, for example, %.4f rounds the number to \(4\) decimal places, adding \(0\)s when necessary. fprintf('a%-2ib', 1) 'a1b' 'a1 b' 'a 1b' 'a-1b' fprintf('a%5.2fb', pi) 'a3.14b' 'a 3.14b' 'a3.14 b' 'a3.142b' input(x) gets a user input in MATLAB syntax. String \(x\) is the prompt. input(x, 's') gets a user input as a string. menu(x, c1, c2, ...) or listdlg('ListString', c1, c2, ..., 'PromptString', x) gets a user input from a list of choices \(c_{1}, c_{2}, ...\), and returns the index. length(input('Enter a string', 's')) and user enters '10' (with the quotes). input('Enter x1', 's') + input('Enter x2') and user enters 10 and 1. '101' '11' opt = ["one", "two", "three"]; opt(menu('Select a string', '1', '2', '3')) and user selects 2. 'two' '2' 'n' load(x, '-ascii') loads the text file with name \(x\). load(x) can load a .mat binary file. readmatrix(x) loads the text or spreadsheet file with name \(x\) into a single matrix. fileread(x) reads the text file with name \(x\) as a string with char type. readlines(x) reads the text file with name \(x\) as a vector of lines, each line has the string type. save(x, v, ..., '-ascii') saves the variables with names \(v, ...\) to the file with name \(x\). save(x, v, ...) saves the variables in a .mat binary file, not human-readable. writematrix(v, x) saves the variable \(v\) to the file with name \(x\). fopen(x, 'w'); fprintf(x, v); fclose(x); writes the string \(v\) to the file with name \(x\). Last Updated: March 03, 2025 at 12:52 AM